Field of Invention
Aspects of this invention are related to endoscopic imaging and are more particularly related to tissue contact detection, displayed scene brightness control, camera auto-exposure control, and illumination control in a teleoperated surgical system.
Related Art
The da Vinci® Surgical System, commercialized by Intuitive Surgical, Inc., Sunnyvale, Calif., is a minimally invasive teleoperated surgical system that offers patients many benefits, such as reduced trauma to the body, faster recovery and shorter hospital stay. One feature of the da Vinci® Surgical System is a capability to provide two-channel (i.e., left and right) video capture and display of visible images to provide stereoscopic viewing for the surgeon. Such electronic stereoscopic imaging systems may output high definition video images to the surgeon, and may allow features such as zoom to provide a “magnified” view that allows the surgeon to identify specific tissue types and characteristics, as well as to work with increased precision.
However, the illumination of a surgical site and the exposure time of a camera used during capture of an image of a surgical site are some of the factors affecting the quality of the images provided to the surgeon. For example, U.S. Pat. No. 8,512,232 B2 describes introducing into a body an endoscope that provides a first level of illumination and also introducing into the body an illumination apparatus that provides a second level of illumination. The second level of illumination is greater than the first level of illumination and is used for imaging a large target area. The lower level of illumination from the endoscope is used for imaging a smaller target area.
However, a potential problem with a high intensity light source has been recognized and a solution provided in U.S. Pat. No. 6,511,422 B1. According to this patent, the output from a high intensity light source is controlled so that whenever the output is not directed at tissue, the light source output intensity is automatically reduced to a safe level. The light reflected from tissue is monitored and if the reflected light indicates that the light source is not directed at tissue, the light intensity is turned down to a safe level.